Combined wheel and disc brake assembly and actuator means therefor



1958 F. D. GRISWOLD 2,858,912

- COMBINED WHEEL AND DISC BRAKE ASSEMBLY AND ACTUATOR MEANS THEREFOR IOriginal Filed Dec. 8, 1955 5 Sheets-Sheet l Nov. 4, 1958 F. D. GRISWOLDCOMBINEDWHEEL. AND DISC BRAKE ASSEMBLY AND ACTUATOR MEANS THEREFOR 5Sheets-Sheet 2 Original Filed Dec. 8, 1955 Nov. 4, 1958 AC OriginalFiled Dec. 8, 1955 F. D. GRISWOLD TOR MEANS THEREFO COMBINED WH- L ANDDISC BRAKE AS BLY AND 5 Sheets-Sheet 3 NOV. 4, 1958 mswo 2,858,912

AND DIS COMBINED WHEEL C BRAKE ASSEMBLY AND ACTUATOR MEANS THEREFOR 7Original Filed Dec. 8, 1955 5 Sheets-Sheet 4 Nov.- 4, 1958 F. D.GRISWOLD 2,858,912 COMBINED WHEEL AND uxsc BRAKE ASSEMBLY AND ACTUATORMEANS THEREFOR 5 Sheets-Sheet 5 Original Filed Dec. 8, 1955 COMBINEDWHEEL AND DISC BRAKE ASSEMBLY AND ACTUATOR MEANS THEREFOR FrederickDaniel Griswold, St. Joseph, Mich., assignor, by mesne assignments, toLambert Brake Corporation, St. Joseph, Mich., a corporation of MichiganOriginal application December 8, 1955, Serial No. 551,759. Divided andthis application May 16, 1957, Serial No. 659,699

5 Claims. (Cl. 188-196) This application is a division of applicationSerial Number 551,759, filed December 8, 1955.

The present invention relates to friction devices, and more particularlyto an improved friction device which constitutes means for rotatablyjournalling a relatively rotatable member such as a vehicle wheel orother r0- tary element and for transmitting torque to or from therotatable member, said friction device having novel operating means foreffecting automatic, adjustment of the friction device coincident withactuation of the friction device.

An object of the invention is to provide a multiple disc brake having astationary disc orplate assembly adapted to be connected to a rigidsupport such as an airplane landing gear strut, said disc or plateassembly having a rotary element such as an airplane wheel mountedthereon, with bearings disposed, between the disc or plate assembly andthe rotary element, thus obviating the need for a separate axle for therotary element or wheel. Disposed between the rotary member and thestationary disc or plate assembly is a number of interleaved discs,including at least one friction disc connected to the rotary member forrotation therewith and an actuator disc carried by the stationary discor plate assembly and operative to effect engagement of the interleaveddiscs with attendant absorption of torque from said rotary element bysaid disc or plate assembly.

Another object of the invention is to provide novel actuator means foreffecting operation of the actuator disc aforesaid, while at the sametime automatically compensating for wear of the discs by limitingrelease movements of the actuator disc to a uniform and only relativelyslight movement as may be necessary to provide a constant releaseclearance between the discs throughout the life of the friction surfacesof the friction device.

A further object is to provide fluid pressure-operated actuator means asaforesaid, including an actuator cylinder having a piston chambertherein, a piston reciprocably disposed in said piston chamber, andself-adjuster means disposed in said piston chamber and operativeresponsive to shifting movements of said piston to automatically adjustand limit movements of said piston in a brake-release direction. In sucha structure, distinct advantages accrue to the self-adjuster means,particularly in a hydraulically operated actuator, by reason of the factthat the adjuster means are bathed in the hydraulic fluid and therebycontinuously lubricated, with attendant long life and ease of operationof the adjuster means.

Specifically, in connection with the actuator means hereof, it is anobject to provide a fluid pressure-operated actuator device including abody having a piston chamber therein, a piston reciprocably disposed inthe piston chamber and adapted to be operatively engaged with a memberto be operated, said body having an adjuster screw threadedly connectedthereto, and said screw and piston being cooperatively interengaged forpermitting said piston to shift freely in one direction, but limitingreturn movement of said piston. In such a structure, the adjuster screwis preferably provided with an enlarged head disposed in an opening insaid piston and having a head surface of substantial area engageablewith a complemental area at the base of the opening in said piston,whereby when the surfaces are engaged,

substantial resistance to turning of the screw relative to the piston isproduced, and the piston is limited in its movement in one direction bysaid screw. On the other hand, in order to enable movement of the pistonin the other direction, without appreciable resistance, the piston isprovided with a thrust element extending beneath the screw head, andanti-friction means are disposed between'said thrust element and thescrew head, whereby when the piston is shifted in the last-mentioneddirection, thrust will be imparted to the screw causing the screw torotate in its threaded mounting and move axial- 1y along with thepiston. Thus, a self-adjusting fluid pressure-operated actuator deviceis provided which has utility in brakes as hereinafter specificallydescribed, as well as in other friction devices, and in any installationwherein automatic adjustment of return movements of an actuator pistonis desired or required.

Still another object .is to provide a combined wheel and brake assemblywherein the wheel is journalled upon the brake instrumentalities whichare in turn secured to a fixed support, such as an airplane landing gearstrut, whereby, for the purposes of rapid service, the entire assembly,including the wheel and brake instrumentalities, may be readily removedfrom the stationary support as a unit, and a similar unit remounted uponthe strut or other stationary support in a very short period of time andwith a minimum of work.

Other objects and advantages will be hereinafter described, or willbecome apparent to those skilled in the art, and the novel features ofthe invention will be defined in the appended claims.

In the drawings:

Fig. 1 is a view in section taken axially through a combined wheel andbrake according to the invention,

and showing the self-adjusting fluid pressure-operated actuator hereof,with certain of the parts shown in elevation;

Fig. 2 is a view partly in section and partly in elevation, as taken onthe line 22 of Fig. 1, showing the brake with the wheel removed;

Fig. 3 is a view partly in elevation and partly in section, as taken onthe line 33 of Fig. 1;

Fig. 4 is an enlarged fragmentary view in section, as taken on the line4-4 of Fig. 2, particularly showing the self-adjusting actuator hereof;

Fig. 5 is an enlarged fragmentary view in section, particularly showingone of the actuator piston chambers and adjuster screw supports; I

Fig. 6 is an enlarged fragmentary view in section, as taken on the line6-6 of Fig. 2, and showing the formation of the operating fluid conduitand one of the cooling air openings through the power plate;

Fig. 7' is a detail view of the power plate in elevation as viewed fromthe outboard side; and

Fig. 8 is an enlarged fragmentary view in section, as taken on the line8-8 of Fig. 7.

Like reference characters of the several figures of. the drawings and inthe following description designate corresponding parts.

For illustrative purposes, a stationary support in the form of anairplane landing gear strut 1. is shown in Fig. 1, said strut 1 beingformed with an enlarged supporting head 2 having a slightly axiallyextended stub shaft or cylindrical support 3 projecting therefrom.Centered on the stub shaft 3 and fixedly secured to the strut PatentedNov. 4, 1958 provided'with a radially extended shoulder 11 adjacent tothe flange 10, and a secondary disc or plate 12 of.

generally annular formation is disposed about the flange in closeengagement therewith and'rigidly secured in abutting engagement with theshoulder- 11 as by means of:

a suitable number of circumferentially. space'd' screws. 13

which project through the secondary disc or plate. -12and intoappropriately threaded openings'in the hub The outer. periphery of thepower plate 7 is. formed with an' annular bearing, seat 1'4, and theoutboard side of the secondary disc or plate 1-2 is provided with. anaxially projecting flange IS on which is formed. another bearing seat16. A pair of anti-friction bearings 17,17

are mounted upon the bearing seats 14 and 16'and have journalled thereona wheel- 18, with the wheel and bearings retained against. axialdisplacement by suitable retainer means; In the illustrative embodimentsuch retainer means includes a shoulder 19 on-power plate 7 and anothershoulder 29 extending inwardly from the wheel 18, with said shoulders 19and 20 disposed at the respective opposite. sides of one of the bearings17.. A

further shoulder 21 is preferably formed on the inner periphery of thewheel 18'and is disposed at the inboard side of the other" bearing 17 inopposed relation. to a threaded retainer ring 22 which is threadedlymounted on the'outer'periphery of the flange 15 on secondarydisc orplate 12. The retainer ring 22 is secured in position as bymeans of atange'd' lock element 23 which is secured at the outboard extremity ofthe flange 15 by, means of a screw 24 or the like, and which projectsinto a slot 22" in the ring 22;

Thus, it will be noted that the wheel is journalled upon the stationarydisc or plate assembly 6, instead of upon an axle as is conventionallydone.

Means are provided for selectively establishing or interrupting thetransmission of torque. from the wheel 18 to the stationary disc orplate assembly 6', said means including a plurality of interleaved discspreferably comprising a plurality of rotors 25 which are keyed to theinner periphery of the wheel 18, a plurality of stators 26 which arekeyed to the stationary disc or plate assembly 6, and a primary actuatordisc or plate 27 which is disposed between the pack of alternate statorsand rotors and the power plate 7'. While a plurality of rotors 25 andstators 26 have been shown in the illustrative embodiment, it should beunderstood that a single rotor may be utilized, or any desired number ofsuch rotors may be utilized, accompanied by one stator between each pairof rotors, as is customary in friction devices of thisgeneral type.

The rotors 25 are preferably keyed to the inner periphery of the wheel18 as by means of a plurality of lugs or keys 18 disposed in spacedrelation about the inner periphery of the wheel, with the respectiverotors 25 being provided with a pair of ears 25 projecting radiallyoutwardly therefrom at opposite sides of each oflthe lugs 18; and thestators 26 are respectively'keyed'to the stationary disc or plateassembly 6 by means of a suitable number of keys 6' which are fixedlysecured in suitably formed grooves 9 in the hub 9 previously'referred toby a pair of screws 28, with each stator 26 being provided with a pairof radially projecting ears 26 on itsinner periphery disposed atrespective opposite sides of the keys 6.

The primary actuator disc 27 is operatively disposed between thesecondary disc or plate 12' and the power plate 7,. with the interleavedstators and rotors previously referred to interposed between the primaryand 4 secondary plates. In this connection, the opposing faces of thepower plate 7 and the primary disc 27 are provided with a plurality ofcircumferentially spaced, opposed and oppositely inclined ramped seats29, 29, in each opposed pair of which there is disposed a camming ball30. The primary disc 27 is centralized and supported upon the balls 30responsive to the action of a plurality of circumferentially spacedbrake release springs 31 which are interposed between the primary disc27' and a corresponding number of spring seats 32 which are formed onthe hub 9 adjacent its free end and project radially outwardlytherefrom, with each spring 31 engaged at one end on a spring seat 32and placed under compression by a spring seat 33 projecting radiallyinwardly from the inner periphery of the primary disc 27. Thus, thesprings 31 maintain a constant pressure on the primary disc 27 tendingto shift the same axially towardsthe power plate. 7, with'the resultthat the balls 30 will be normally maintained in the deepest parts ofthe ramped seats 29, 29, and the primary disc 27 will be floatinglysupported upon the balls 30 for axial shifting. movements, as well asfor rotative movements,

whereby initial actuation and a powerful self-energizing action,respectively, are effected.

In order to effect initial actuation of the brake, a plurality of fluidpressure-operated actuator devices are disposed inv equi-distantlyspaced relation adjacent to the outer periphery of the power plate 8,each actuatordevice comprising a piston chamber 34 formed in theoutboard side of the power plate 7. Each piston chamber 34"is adapted toreceive and has reciprocably mounteditherein an actuator piston 35,.saidpistons each having about its outerperiphery a seal-receiving groove 36in which is disposed an. O-ring seal 37. During casting of the powerplate 7,.it is preferably provided withcored passageway 38 whichestablishes fluid communication'between. the respective piston chambers34, this passageway 38" also communicating with a fluid inlet-outletport 39 'a'nd a bleed' port 40. The inlet-outlet port 39 is adaptedbymeans of a fitting 41 to be connected witha's'ource of fluid underpressure (not shown). Thus, when fluidunder pressure is admitted to thepassageway 38' through the inlet-outlet passageway 39, the fluid will bedistributed to each of the piston chambers 34 and will shift'th'erespective pistons 35 axially and outwardly of the piston chambers 34'and shift the primary discs 27' towards the secondary disc or plate 12,thereby gripping'the interleaved stators and rotors between the primaryandsecondary discs to effect engagement of the brake.

Upon initial engagement of the brake, the rotor 25 which is engaged bythe primary disc 27 will impart drag t'orque to the primary disc 27tending to cause thelatter'to' rotate along with said rotor 25,whereupon a slight relative rotation of the primary disc 27 with respectto'the power plate 7 will be effected, resulting in a'camming action ofthe balls 30in the opposed seats 29, 29, thus instigating a powerfulself-energization of the brake in proportion tothe load thereon.

Inview of the fact that such'self-energization of the brake depends uponrotation of the primary disc 27 slightly with respect to the power plateand therefore with respect to the pistons 35, an insert 42 having a lowcoefiicie'ntof friction is preferably disposed in a recess in the'outerend of each piston 35 for engagement with the contiguous face of theprimary-disc 27, whereby frictional resistance to such rotation of theprimary disc 27 is minimized.

In.view of the foregoing, it is apparent that a highly the connection ofthe stationary disc or plate assembly 6 to the supporting head 2 of thestrut 1, the entire wheel and brake assembly may be readily removed fromthe strut with a minimum of effort, and a corresponding ne'w'or rebuiltassembly may be expeditiously remounted upon the strut 1 in an equallyfacile manner, thus enabling very rapid service of aircraft equippedwith such a combined wheel and brake assembly.

In accordance with another of the salient features of the invention,means are provided for effecting automatic or self-adjustment of theactuator devices by limiting inward movement of the pistons in thepiston chambers to compensate for wear of the friction discs. Suchautomatic or self-adjuster means includes a one-way shiftable memberpreferably in the form of an adjuster screw 43.

Integrally formed with the backing or power plate 7 in each'pistonchamber 34 is an axially extended boss or internally threaded screwsupport 44 through which the screw 43 extends and in which said screw isthreadedly supported, with the lead end of said screw projecting throughan opening 45 in the power plate 7 externally of the power plate, andthe other end of said adjuster screw 43 being provided with a head 46having a relatively flat face 47 disposed for engagement with acomplemental face interiorly of the respective pistons 35. The head 46of each screw is extended radially so as to overlie a snap ring 48 whichis mounted about the inner peripheries of the hollow pistons 35, andantifriction means preferably in the form of a ball bearing or the likeis interposed between the snap ring and the screw head. The screw 43 andits threaded mounting of each adjuster is preferably provided with ahigh-pitch, multiple lead thread which is so constructed as to permitthe screw to be easily rotated in response to axial thrust imposedthereon beneath the screw head 46 by the hearing 49, so that the piston35 of each actuator device will be free to shift axially in abrake-engaging direction to the full extent necessary to effect fullengagement and to take up any wear. However, the bearing 49 of eachadjuster is so proportioned as to allow a slight axial clearance spacebetween the bearing and the underside of the screw head, so that thepiston 35 of each actuator will be free for axial movement in a brakeengaging direction without effecting any axial force on the screw, thusto take up the required release clearance of the brake, as isrepresented by the exaggerated space between the primary disc 27 and theadjacent rotor 25 and by the gap between the bearing 49 and the underside of the screw head 46, as particularly shown in Fig. 4. Therefore,it will be noted that the adjuster is operative to take up wear of thefriction faces of the brake, and the brake will always be provided witha substantially constant release clearance. Return movements of thepistons 35 in their respective piston chambers 34 beyond the distancerequired to provide the aforementioned release clearance is precludedupon abutment of the face 47 of the end wall of the respective pistons35 with the respective adjuster screw heads 46. The substantial areas offrictional engagement between each screw head 46 and piston face 47effectively resists retrograde rotation of the screws.

Means are also provided for preventing the leakage of operating fluidpast the respective adjuster screws 43 through their threaded supports44. Preferably, such means is in the form of an O-ring seal 50 which isdisposed in an appropriate recess in the power plate 7 extending aboutthe periphery of the opening 45 through which the adjuster screw of eachadjuster extends, said O-ring seals engaging the respective adjusterscrews 43 adjacent their lead end to prevent such leakage. In addition,it has been found that afurther desired and improved result isaccomplished by said O-ring seals 50 by virtue of the fact that theyeliminate the need for any further means for preventing overrun of theadjuster screws during brake operation. Sufficient frictional eii=gagement of the O-rings 50 with their respective adjuster screws 43resists free rotation of the adjuster screws to the extent necessary toprevent overrunning, whereas in previous screw adjusters of a knowntype, it was necessary or desirable to provide special means foreliminating such overrunning.

In operation of the brake described in the foregoing, fluid underpressure will be admitted to the passageway 38 from a suitable source(not shown) and distributed to the respective fluid pressure-operatedactuator devices in the power plate 7. The initial application of fluidpressure to each actuator device will cause the respective pistons 35 tomove axially outwardly of their piston chambers 34, thus shifting theprimary disc 27 axially towards the secondary disc or plate 12 againstthe brake-release pressure of the springs 31. Upon initial frictionalengagement of the interleaved friction discs, including the primary disc27 and the rotors and stators 25 and 26, respectively, as they arepressed axially towards the secondary disc or plate 12, drag torque ofthe rotor 25 whichis engaged with the primary disc 27 will effect slightrotation of the latter disc relative to the stationary power plate 7,with the result that the balls 30 will cam the power plate 7 and primarydisc 27 axially apart to engage the brake with a powerful servo orself-energizing action. Any wear of the friction surfaces will becompensated for so that a constant release clearance is maintained asthe respective adjuster screws 43 in each actuator are caused to shiftaxially along with the actuator pistons 35 a distance equal to the wearto be compensated for, but are prevented from retrograde movement byvirtue of resistance to opposite rotation of said screws as caused bythe engagement of the screw heads with the end walls of the pistons 35.

Substantial heat is usually generated during brake op eration, and inorder to prevent the conduction of heat from the friction discs tothefluid in the actuator devices, the primary'disc 27 and the secondarydisc or plate 12 are each preferably provided with friction facingmembers as at 27 and 12, respectively, such facing members being securedto the respective discs as by rivets 52, but with an intervening layerof insulating material as at 53. On the other hand, it will be notedthat the power plate 7 is provided with a plurality of circumferentiallyspaced openings 54 therethrough, whereby cooling air is free tocirculate through the openings 54 into the area of the friction discs.

In addition, the hub 9 of the stationary disc or plate assembly 6 isprovided with a plurality of circumferentially spaced openings 55through which air is free to pass, and the secondary disc or plate 12 isprovided at its central portion with a reinforcing or supporting plug 56having a central opening 57 therethrough, this central opening 57permitting the ingress of air into the hub 9, from whence it may alsopass upwardly through the friction discs to cool the same, while theplug 56 functions to add rigidity and support the weight of the wheel 18on the bearing 17 which is mounted upon the secondary disc or plate 12,thus relieving the hub 9 of the load of the wheel.

While the specific details of the invention have been herein shown anddescribed, changes and alterations may be resorted to without departingfrom the spirit thereof as defined in the appended claims.

I claim:

' l. A fluid pressure-operated motor comprising a member having a pistonchamber therein and also having a fluid inlet and outlet forestablishing communication between a source of pressure fluid and saidpiston chamber, a piston reciprocably disposed in said piston chamber,one-way shiftable means cooperatively interengaged with said piston andwith the member having the piston chamber for allowing unlimitedmovement of said piston outwardly of said piston chamber and limitingreturn inward movement of said iston, said one=way shiftable meansincluding a screw, the member having the piston chamber being providedwith a complemental screwthreaded opening in which said screw isthreadedly mounted, said piston having an opening at its inner end, andsaid'screw projecting'in'to' said lat'ter'piston opening into abuttingcontact with said piston to prevent inward movement of said piston, andsaid screwandpiston having cooperative means' for effecting rotation andconsequent axial movement of said screw along with said'piston uponoutward movement of said piston.

2. A fluid pressure-operated motor comprising a member having a pistonchamber therein and also having a fluid inlet and outlet forestablishing communication between a source of pressure fluid and'saidpiston chamber, a piston reciprocably disposed in said piston chamber,one-way shiftabl'e means cooperatively interengaged with said piston andwith th'eme'mber having'the'piston" charn ber forallowin'gunlimited'movement of said piston'outwardly of said piston chamberandlimiting return inward' movement of said piston, said one-way shiftable'means including a screw, the memberhaving the pistonch'a'mber beingprovided with a complementalscrew-threadedopening in whichsaid'screw isth'readedly'mounted, said piston having an opening at its inner end, andsaid screw projecting into said latter'piston openingand having an en'-larged head disposed in said opening in abutting contact with saidpiston to prevent inward movement of said piston, said pistonhaving athrust shoulder'pr'ojectinginto the opening therein behind said screwhead, and antifriction thrust transmitting means between said thrustshoulder and said screw head for impartingaxial'thrust' to saidscrewhead with'consequent rotationof said screw for shifting said screwaxially along with said piston upon outward movement of said piston.

3. A fluid pressureoperated motor comprising'a' member having a pistonchamber therein and also having a fluid inlet and outlet forestablishing communication between a source of'pressure fluid and saidpiston-chamber, a piston reciprocably disposed in said piston chamber,one-way shiftable means cooperatively interengaged with said piston andwith the member'having the piston chamber for allowing unlimitedmovement of said piston outwardly of said piston chamber and limitingreturn inward movement of said piston, said one-way shiftable meansincluding a screw, the member having the piston chamber. being providedwith a complemental screw-threaded open ing in which said screw isthreadedly mounted, said piston having an opening at its inner end, andsaid screw p'rojecting into said latter piston opening and having anenlarged head disposed in said opening in abutting contact with saidpiston to prevent inward movement of said piston, said piston having athrust shoulder projecting into the opening therein behind said screwhead, and anti-friction thrust transmitting means between said thrustshoulder and said screw head for imparting axial thrust to said screwhead with consequent rotation of said screw for shifting said screwaxially along with said piston upon outward movement of said piston, thethickness of said thrust transmitting means being slightly less than thedistance between the screw head and the thrust shoulder aforesaid.

8 4. A fluid pressure=operated motor comprising a member having a pistonchamber therein and also having a fluid inlet and outletfor establishingcommunication'betwe'ena source of pressure fluid and said pistonchamber, a piston reciprocably disposed in said piston chamber,

one-way shiftable means cooperatively interengagedwith' tact with saidpiston to prevent inward movement of said piston, and said screw andpiston having cooperative means for effecting rotation and consequentaxial movement of said screw along with said piston upon outwardmovement of said piston, said screw and the opening in which the screwis mounted having complemental annular surfaces in close engagement withone another, one'of said' surfaces having an annular seat therein, and

an annular seal disposed in said seat and closely engaged with the outersurface for sealing the piston chamber against leakage of pressure fluidpast said screw.

5. A fluid pressure-operated motor comprising a member having a pistonchamber therein and also having a fluid inlet and outlet forestablishing communication betweena source of'pressure fluid and saidpiston chamber, a piston reciprocably disposed in said piston chamber,one-way shiftable means cooperatively interengaged with said pistonandwith'the member having the piston chamber for allowing unlimitedmovement of said piston outwardly of said piston chamber and limitingreturn inward movement of said piston, said one-way shiftable meansincluding a screw, the member having the piston chamber being'providedwith a complemental screw-threaded opening in which said screw isthreadedly mounted, said piston having an opening at its inner end, andsaid screw projecting into said latter piston opening into abuttingcontact with said piston to prevent inward movement of said piston, andsaid screw and piston having cooperative means for effecting rotationand consequent axial movement of saidscr'ew along with said piston uponoutward movement of said piston, and means for preventing overrunning ofsaid screw comprising a resilient seal closely gripping said screw andclosely fitting in the opening in which the screw is mounted forfrictionally resisting rotation of said screw and for sealing thescrew-mounting opening against leakage of pressure fluid from saidpiston chamber.

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